Speaker
Description
Transitional millisecond pulsars (tMSP) represent a dynamic category of celestial sources that establish a crucial connection between low-mass X-ray binaries and millisecond radio pulsars. These systems exhibit transitions from rotation-powered to accretion-powered states and vice versa, highlighting the tight evolutionary link expected by the so-called recycling scenario. In their active phase, these sources manifest two distinct emission modes named high and low, occasionally punctuated by sporadic flares.
In this talk, I will present high time-resolution optical spectroscopic observations of the prototypical tMSP J1023+0038 in its sub-luminous disc state. The dataset allows us to probe the system on minute timescales, revealing pronounced variability in the colour and in the properties of the main emission lines, including changes in line strength and profile. I will discuss how this short-timescale variability provides new insight into the structure and dynamics of the accretion flow and its interaction with the neutron star during its disc state.